1. Field of the Invention
This invention relates to surface modified resinous articles, and processes for making same, and more particularly, to an improved method and composition for making said articles in a continuous manner.
2. Description of the Prior Art
In the aforesaid copending patent application, there is described a method of incorporating a modifier ingredient such as a U.V. absorber into the surface region of a resinous body, e.g. a PVC sheet. The method includes the steps of: (1) immersing the body in a liquid such as water and (2) contacting the immersed body with a solution of the modifier ingredient in a solvent such as methylene chloride which is immiscible with the liquid and which will swell the surface of the resin to allow the solution to enter its surface region.
In the continuous mode of practicing this process, the solution is present as a lower layer, water is the upper layer, a continuous polymer sheet article is transported through the water, and the solution is pumped from the lower layer into the upper layer and directed onto the top surface of the sheet for a predetermined contact time during which time the modifier ingredient is incorporated into the contacted surface. After the solution is applied, a jet of water is directed onto the treated surface to displace any residual solution remaining thereon.
When this process is run for an extended period at room temperature, however, it is observed that a solid precipitate of U.V. stabilizer material accumulates on the surface of the water layer. This solid material circulates throughout the system which tends to clog the pumping and piping equipment used both for applying the solution to the resin surface and for displacing residual solution thereon.
While suitable filters and/or skimmers may be used in the system to remove the solid material floating on the surface of the water layer, such equipment is relatively costly and requires periodic maintenance.
Accordingly, it is an object of the present invention to provide a method for preventing the accumulation of solid precipitate material which appears on the surface of the water layer in the surface modification process of the aforesaid patent application.
A more particular object herein is to provide a system, composition and method for substantially eliminating the problem of solid formation on the surface of the water layer in such process.
A feature of the invention is the use of a surfactant to change the wetting characteristics of the air-water, or water-surface modifier solution interfaces, or both interfaces, so that solid modifier ingredient does not form on the surface of the water layer.
Another feature herein is the provision of a surface modification system which includes an upper water layer, a lower modifier solution layer, and a surfactant in one or both of said layers.
Still another feature of the invention is the provision of a surface modifier composition which includes a modifier ingredient, a resin-swellable, water-immiscible solvent, and a surfactant, and a process for incorporating said modifier ingredient from said composition into the surface region of a resinous body in a continuous matter without forming unwanted solid material therein.
These and other objects and features of the invention will be made apparent from the following more particular description thereof.